A Answers (3)
Egilius Spierings, MD, Neurology, answeredDuring a migraine attack, altered cerebral blood flow and electrical activity occur first in the primary visual cortex, which may help explain why visual disturbances often accompany the aura. Symptoms affecting the extremities, such as numbness and tingling, may occur when the spreading depression reaches the primary sensorimotor cortex. The spreading depression usually stops about halfway across the brain. At that point, a parallel process, involving a combination of blood vessel dilation and inflammation, may be causing headache pain. Bolstering this theory is the fact that a resting brain is more susceptible to spreading depression than an active one, which may explain why migraine attacks often strike as people unwind after a stressful period.Helpful? 1 person found this helpful.
Dawn Marcus, Neurology, answeredWhen a person with a lowered threshold to headache comes in contact with a trigger, a series of events begins. Sometimes migraine triggers are obvious, like drinking red wine, having your menstrual period, or having a stressful day; other times, triggers are less clear and may be internal changes in the body of which we're unaware.
After the migraine process has been initiated, nerve cell activity in the back of the brain (the occipital, or visual, cortex) begins moving to the front to the brain. This wave of nerve activity is noted on both sides of the brain. The wave initially causes the nerve cells to be less active, and a wave of increased nerve activity follows. Because migraine activity often begins in the part of the brain affecting vision, many migraine sufferers experience visual changes during their attacks, such as migraine auras and blurred vision. An area of the brain called the hypothalamus is also activated. This causes the vague feelings of irritability, anxiety, hyperactivity, food cravings, and increased urination that are reported as prodrome symptoms by some people with migraine.
As the nerves become activated, the ends of the nerves next to blood vessels in the scalp (outside the skull) release certain chemicals, such as serotonin, which cause the blood vessels to expand or dilate and become inflamed. These expanded blood vessels cause an increase in the blood flow around the brain. As a result, you may notice that the blood vessels at your temples increase in size and are tender. Other chemicals are also released from the nerve endings, leading to more dilated and inflamed blood vessels. These dilated, inflamed blood vessels further stimulate the nerve endings to release more chemicals, thereby amplifying the process.
Once nerve activation starts, nerves located in the brainstem begin to send migraine messages throughout the brain. Pain signals are transmitted to the muscles in the neck, which become stiff and painful. This causes the neck pain that is often seen during both the prodrome and headache phases of migraine. Pain signals also travel to the part of the brain sometimes referred to as the "nausea center," resulting in loss of appetite, nausea, and sometimes even vomiting. Pain messages also travel to pain centers in the brain, further amplifying the pain response. Resulting in what some people call a "full-blown" migraine.
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During a migraine attack there are many symptoms that can develop. The most common symptoms include: headaches (normally over one or both sides of the forehead), sensitivity to light or sound, nausea and even vomiting. These are the symptoms of classic migraines. Sometimes people get a feeling that they are about to get a headache. This is called an aura and can include blurry vision, weird smells, spots of light in the vision or even just a warning feeling. However, there are more complex forms of migraines, as well, which can include abdominal pain, numbness, tingling or weakness in the face or extremities. If these symptoms develop, you should see your doctor right away to be sure the symptoms are due to migraines and not something worse such as stroke.